The present invention is especially directed to the solution of various problems encountered by sign manufacturers in the construction and maintenance of internally illuminated and similar signs. Signs of this type are widely employed and their construction constitutes a substantial portion of the business of most sign manufacturers. Signs of the type with which the present invention is concerned often take the form of a relatively narrow hollow box in which one (single faced) or both (double faced) of the major sides are formed by translucent sign display panels. Fluorescent tubes mounted within the interior of the sign are employed to back light the display panels. Because the display panels possess little structural strength, the panels are mounted in a peripheral frame which supplies the necessary structural strength for the sign, provides a support for in the fluorescent tubes and also provides an enclosure for the electrical wiring and other components of the illumination system. The present invention is especially directed to the frame assembly of such signs.
Extruded aluminum shapes are quite commonly employed in the construction of sign frames of the type under consideration -- see, for example, my previously issued U.S. Pat. No. 3,235,989. While literally thousands of extruded aluminum shapes are available to the sign industry, the very fact that such a large number of shapes are available is evidence of a continuing search in the industry for improvements in this field. This, in turn, indicates a lack of satisfaction with presently available designs.
The present invention is especially designed to overcome some of the problems most commonly encountered by prior art sign frame constructions. With an inventory of a small number of standardized shapes according to the present invention, a manufacturer is able to construct rectangular or polygonal signs of a wide range of sizes, of single or double face construction, and in which a display panel may be detachably clamped in place or hingedly mounted. The present invention also enables the construction of a sign in a manner such that the interior of the sign is readily accessible for cleaning, replacement of burned out lights or for maintenance and repair of the electrical power system. By minimizing the number of stock parts required to maintain an adequate inventory for custom sign construction, the sign manufacturer is able to order individual parts in relatively large quantities, thus obtaining a volume discount. Further cost reductions are achieved by the design of the individual shapes in a manner such that, in assembly, the assembled parts cooperatively strengthen each other and enable the employment of lighter and, hence, less expensive extrusions.